Hindered phenolic derivatives of certain phosphinodithioic acids or an o o-diester of phosphorothiolothionic acid

ABSTRACT

HINDERED PHENOLIC DERIVATIES OF CERTAIN PHOSPHINODITHIOIC ACIDS AND O,O-KIESTERS OF PHOSPHOROTHIOLOTHIONIC ACIDS ARE PREPARED BY THE ADDITION OF (A) AN ALPHA, BETAUNSATURATED ESTER OF A HINDERED HYDROQUINONE AND (B) A PHOSPHINODITHIOIC ACID OR AN O,O-DIESTER OF PHOSPHOROTHIOLOTHIONIC ACID. COMPOUNDS ARE OBTAINED WHICH HAVE THE FORMULA   Q2-P(=S)-S-C(-R1)(-R2)-CH(-R3)-COO-R   WHEREIN-Q IS-R4 OR OR4 -R IS   2-(LOWER ALKYL-),4-(HO-),(LOWER ALKYL)-PHENYL   WHERE SAID (LOWER)ALKYL HAS FROM 1 TO 6 CARBON ATOMS; -R1, R2, -R3 ARE EACH HYDROGEN, LOWER ALKYL FROM 1 TO 6 CARBON ATOMS, PHENYL, BENZYL OR   -CMH2MCOOR   WHERE M IS 0 TO 6; -R4 IS ALKYL FROM 1 TO 24 CARBON ATOMS, CYCLOAKYL FROM 1 TO 6 CARBON ATOMS, PHENYL AND BENZYL AND WHEN Q IS -OR4 THE TWO -R4 GROUPS CAN BE -(CH2)N-, WHEN N IS 2 OR 3, FORMING A CYCLIC O,ODIESTER OF PHOSPHOROTHIOLOTHIONIC ACID. THE COMPOUNDS ARE USEFUL AS STABILIZERS FOR ORGANIC MATERIALS WHICH ARE SUBJECT TO OXIDATIVE AND THERMAL DETERIORATION.

United States Patent 3,639,538 HINDERED -PHENOLIC DERIVATIVES 0F CER- TAIN PHOSPHINODITHIOIC ACIDS 0R AN 0,0- DIESTER 0F PHOSPHOROTHIOLOTHIONIC ACID Eduard K. Kleiner, Dobbs Ferry, N.Y., assignor to Ciba- Geigy Corporation, Ardsley, N.Y- No Drawing. Filed Jan. 31, 1969, Ser. No. 795,696 Int. Cl. C07f 9/16, 9/32, 9/40 US. Cl. 260941 Claims ABSTRACT OF THE DISCLOSURE Hindered phenolic derivatives of certain phosphinodithioic acids and 0,0-diesters of phosphorothiolothionic acids are'prepared by the addition of (a) an alpha, betaunsaturated ester of a hindered hydroquinone and (b) a phosphinodithioic acid or an 0,0-diester of phosphorothiolothionic acid. Compounds are obtained which have the formula (lower) alkyl where said (lower)alkyl has from 1 to 6 carbon atoms;

R R R are each hydrogen, lower alkyl from 1 to 6 carbon atoms, phenyl, benzyl or Where m is 0 to 6;

R is alkyl from 1 to 24 carbon atoms, cycloalkyl from 1 to 6 carbon atoms, phenyl and benzyl and when Q is OR the two -R groups can be (CH where n is 2 or 3, forming a cyclic 0,0- diester of phosphorothiolothionic acid.

The compounds are useful as stabilizers for organic materials which are subject to oxidative and thermal deterioration.

The present invention is concerned with novel compounds which are useful as antioxidants for organic materials and particularly, as antioxidants for synthetic polymers such as, for example, polypropylene, polyethylene, polyesters, polystyrene, polyvinylchloride, nylon and other polyamides, cellulosics, polyacetals, polyurethanes, petroleum and wood resins, mineral oils, animal and vegetable fats, waxes, rubbers such as styrenebutadiene rubber (SBR), acrylonitrile-butadiene-styrene rubber (ABS), olefin-copolymers, ethylene-vinyl-acetate copolymers, polycarbonates, polyacrylonitrile, poly(4-methyl pentene-l) polymers, polyoxymethylenes, and the like. The present invention also relates to a novel procedure for preparing the aforesaid novel antioxidants and to stabilized compositions containing said novel antioxidants.

The prevention of oxidation of various organic materials is obviously of primary industrial concern and therefore, antioxidants are used in or added to a wide variety of commercial products such as synthetic polymers of the ice type indicated supra, oils, plastic materials, etc., which are normally subject to oxidative deterioration.

The novel antioxidants of the present invention are represented by the following formula:

R1 R3 Q1P (8) $45-$11 I'm 000R FORMULA I wherein --Q is -R or OR R is (lower) alkyl (lower) alkyl R R R are each hydrogen, lower alkyl, phenyl,

aralkyl or C H COOR, where m is 0 to 6 -R is alkyl, cycloalkyl, phenyl, aralkyl and when Q is OR the two R groups can be (CH where n is 2 or 3, forming a cyclic 0,0-diester of phosphorothiolothionic acid.

As used herein, alkyl covers groups having from 1 to 24 carbon atoms, and preferably from 1 to 12 carbon atoms. Illustrative examples of such groups are methyl, ethyl, isopropyl, n-butyl, t-butyl, n-hexyl, n-octyl, n-decy'l, n-dodecyl, n-hexadecyl, eicosyl, tetraeicosyl and the various branched chain isomers thereof. By lower alkyl is meant alkyl groups having from 1 to 6 carbon atoms. Cycloalkyl includes cycloalkyl groups having up to 6 carbon atoms, such as cyclobutyl, cyclopentyl, cyclohexyl. Aralkyl covers phenyl substituted alkyl groups having up to 24 carbon atoms. In addition to alkyl substitution the phenyl groups may also be substituted with chlorine, bromine, alkoxy, hydroxyl, alkylthio or a carboalkoxy group. Illustrative examples of aralkyl groups are benzyl, phenylethyl, 2,4-dibutylphenyl, 2,4,6-trihexylphenyl, 2-chlorotolyl, 4-hydroxy-3-methyl-phenyl, 4-ethoxyphenyl, 4-butylthiophenyl, 3-hydroxy-4-ethylthiophenyl and the like. Where R R or R is C H m is 0 to 6, but preferably 0 or 1.

The novel antioxidants of the present invention are the addition products of (a) an cap-unsaturated ester of hindered hydroquinone of the formula R COOR and (b) a phosphinodithioic acid or a 0,0-diester of a phosphorothiolothionic acid of the formulae and (R P(S)SH respectively, wherein -R, R R R R are as defined above. The addition reaction involving the 0:,[3-1111S3l111'8i6d ester and a phosphinodithioic acid or a 0,0-diester of a phosphorothiolothionic acid is effected by heating equivalent amounts of the reactants in an inert solvent at temperatures from about 30 to about C. as described in Houben-Weyl, Methoden der Organischen Chemie, vol. XII/1 (1963) page 284 and vol. XII/2 (1964), page 683 (Georg Thieme Verlag, Stuttgart). A catalytic amount of base may be used to speed up the condensation reaction, especially if lower condensation temperatures are employed. Preferred bases are alkoxides such as sodium or potassium methoxide or ethoxide, organic bases such as piperidine, triethylamine, picoline or benzyltrimethylammonium hydroxide and the like.

Thenovel antioxidants of this invention were prepared by using the following general procedure:

Equimolar amounts of the a,fi-unsatnrated ester and the phosphingdthioic acid or 0,0-diester of a phosphorothiolothionic'acid are dissolved in 2 to 3 times the amount of chloroform or benzene and sealed under nitrogen. The reaction vessel is kept at about 80 C. for 12 to 20 hours until the conversion is complete as checked by thin layer chromatography. The reaction mixture is then washed with a saturated sodium bicarbonate solution and water, and then dried over sodium sulfate. Then the solvent is evaporated and the crude product purified either by distillation or by crystallization or by filtering the solution through neutral aluminum oxide. Yields are high, that is, generally over 80%.

Illustrative a,fl-unsaturated esters used in preparing the antioxidants of the present invention as indicated above, are represented by the following formula:

C=C R C O O R wherein -R is (llower) alkyl (lower) alkyl and R R and R are as defined above.

Examples of such esters are:

R R Ra Esters 0i:

Acrylic acid --H H Methaerylie acid.. H -CH Crotonic acid-.. -CH3 -H -H Clnnamic acid. -CH5 -H H Fumaric aeid.- COOR H -H Maleic acid. H C0O R H Mesaconic acid. C O O R H -CHa Citraconic acid --COOR CHa Itaconle acid... H -H CH2CO0 R Aconltie acld.- -COOR -H -CH1COO R The preferred tsp-unsaturated esters are esters of acrylic acid, fumaric and itaconic acid. The preferred phosphinodithioic acid used in preparing antioxidants represented by Formula I where Q is -R are dialkylphosphinodithioic acids such as diphenyland dibenzylphosphinodithioic acids.

Illustrative examples of phosphinodithioic acids are 4 are described in Houbenheyl, ibid., vol. XII/1 (1963), pages 269-272.

The preferred 0,0-diesters of phosphorothiolothionic acid used in preparing antioxidants represented by Formula I where --Q is OR are the dialkylesters with straight or branched chain alkyl groups having from 1 to 18 carbon atoms, diphenyl and diaralkylesters.

Illustrative examples of 0,0-diesters of phosphorothiolothionic acids are cyclic 0,0-diesters of phosphorothiolothionic acid such as 2-mercapto-2-thiono-1,3,2-dioxaphospholane, Z-mercapto-Z-thiono-4,5-dimethyl-1,3,2-dioxaphospholane and the like.

These 0,0-diesters of phosphorothiolothionic acids are well known and are described in Houben-Weyl, ibid., vol. XII/2. (1964), pp. 683-689.

Some of the preferred starting a,fi-unsaturated ester compounds used in preparing the antioxidant compounds of the present invention are as follows:

(a) 3,S-di-tert-butyl4'hydroxyphenyl acrylate (b) 3,S-di-tert-butyl-4-hydroxyphenyl methacrylate CH =C(CH )COOR (c) bis(3,5-di-tert-butyl-4-hydroxyphenyl) fumarate COOR H COORo (d) bis(3,5-di-tert-butyl-4-hydroxyphenyl) itaconate The above listed a,;3-unsaturated esters were reacted with the following phosphinodithioic acids and 0,0-diesters of phosphorothiolothionic acid: (e) diphenylphosphinodithioic acid a 5)2 (f) 0,0,-diethyl hydrogen phosphorodithioate 2 5 )2 (or diethyldithiophosphate) Table I below contains illustrative examples of the antioxidants of this invention with some of their properties. These antioxidants have been prepared by the addition of the diphenylphosphinodithioic acid and 0,0-diethyl hydrogen phosphorodithioate to the a e-unsaturated ester according to the general procedure described above.

TABLE I.NOVEL AN'IIOXIDANIS AND THEIR PROPERTIES Melting or boiling point C.) Starting Appearance crystallized from materials Product (A) .Slightly yellow viscous oil"-.. Purified by aluminum oxide (a) plus (e) 3,5-di-t-butyl-4-hydroxyphenyl 3-(diphenylphosphinothioylchromatography. thio)propionate R 0COCH2OH2S(S)P(CuH5)2 (B)... White powder M.P. 117-119 cyclohexane (c) plus (e) Bis(3,5-di-t-butyl-4-hydroxyphenyl) 2-(diphenylphosphin0- thioylthio)sueeinate ROOCOCHS(S)P(CQH5)Q R00 CO CH2 (0) ..do M.P. 54-56 heptane/cyclohexane. ((1) plus (e) Bis(3,5-di-t-butyl-4-hydroxyphenyl) 2-(diphenylphosphinothioylthiomethyl) succinate R OCOCHCH2 tH5)Z R OCO CH2 (D)... Colorless viscous oil Purified by aluminum oxide (1)) plus (i) 3,5-di-t-b tyli-hydroxyphenyl 2-methyl-3-(dicthoxyphoschromatography. phinothioylthio)propionate RQOCOCH(CH3)CH2S(S)P(OC2H5)2 (E). White crystals M.P. 80-85 hexane n (0) plus (i) B s(3,5-di-t-butylAhydroxyphenyl) 2-(diethoxyphosphinothioylthio)succinate R 0 COCHS (S) P (O C2H5)2 R 0 CO CH (1) do M.P. 57-61 ((1) plus (i) B s(3,5-di t buty1'4-hydroxyphenyl 2-(dietlioxyphospl1inotllioylthiomcthyl)suecinate RDOCOCHCH2S(S)P(OC2H5)2 R OCO H2 esters comprises reacting an alcohol dissolved in pyridine With an acid chloride. For example 2,6-di-t-butylhydr0- quinone and acrylyl chloride yield 3,5-di-t-butyl-4-hydroxyphenyl acrylate; 2,6-di-t-butylhydroquinone and methacrylyl chloride yield 3,S-di-t-butyl-4-hydroxyphenyl methacrylate; 2,6-di-t-butylhydroquinone and fumaryl chloride yield bis(3,5-t-butyl-4-hydroxyphenyl)fumarate; 2,6-di-t-butylhydroquinone and itaconyl chloride yield bis- (3,5-di-t-butyl-4-hydroxyphenyl) itaconate.

TABLE II Novel antioxidants Phosphinodithioic acids and O, O-diesters of phosphorothiolothionic acids 01, B-unsaturated esters 1 Novel antioxidants G CH PSSH ROCOCHSSPCH 2 m CHCOOR 1) (trans) 2 z Roooocm H CH 2P S)SH R OCOCHS(S)P(CH)z 9) z onooom) (trans) o 4 9 2 1100000112 (I) (CBH5CH2)2P S)SH CH2=CHCOOR0 ROOCOCH2CH2S(S)P(CH2CBII5)2 (J) (pCH3C5H4)2P(S)SH CHz=CHCOORn RoOCOCHzCHzS(S)P(C@H4CH (K) (p-ClCaH )gP(S)SH CH =(|3COORo RoOCOCHCHzS(S)P(C6HiCl)z CHzCOOR RGOCOCHZ L CH O 2P S SH ROOCOCHS(S)P(OCH a n CCHCOORO) (trans) 5 u 2 1100000112 M ono P 3 SH RoOCOCHS(S)P 0011M 6 5 )2 :/CHCOORO) (trans) G 5 2 RDOCOCHg (N). (CQH5CHQO)2P(S)SH CHE=C(CH3)COORO ROOCOCH(CH3)CH2S(S)P(OCI'I2COH5)2 (0)-- (CH CHzO)zP(S)SI-I CH =CHCOORu R OCOCH3CHgS(S P(OCH2CH2CaH (P).- CHz-O CH2=CCOOR0 /OCH;

P(S)SH CHzCOORu RoOCOCHCH2S(S)P\ CH2O RoOCOCHa O-CH2 (Q) ..CH3CHO CHz=CCOORu /O]CHCH P(S)SH CHgCOORu RuOCOCI-ICH2S(S)P\ CH CH-O RoOCOGHz OCH--CHa 1 R0=@-on, 3, 5-di:t-butyl-4-hydrozyphenyl.

After the precipitated hydrochloride is removed, the reaction liquid is evaporated yielding crude product which is purified either by distillation or recrystallization.

The oxidation of most polymers is so slow at ambient temperatures, even in the absence of antioxidants, that testing of the effects of antioxidants must necessarily be conducted at high temperatures in order to yield results within a convenient period of time. The tests conducted on the materials listed in the following tables were conducted either in a tubular oven with an airflow of 400 cubic feet per minute at an oven temperature of 150 C. or in a rotary oven with 4 rpm. at an oven temperature of 150 C. The oven ageing is set out in hours.

In preparing the sample for testing, unstabilized polypropylene powder is thoroughly blended with the indicated antioxidant. The blended material is thereafter milled on a two-roller mill at a temperature of 182 C. for six minutes after which time the stabilized polypropylene is sheeted from the mill and allowed to cool. The milled polypropylene sheet which has been stabilized is then cut into small pieces and pressed for seven minutes on a hydraulic press at 218 C. and 174 psi. pressure. The resultant sheet of 25 mil thickness is then tested for resistance to accelerated ageing in the above described tubular oven. II1-Tab1es III and IV are reported the results of the oven ageing tests in which the antioxidants of this invention were added to polypropylene together with the indicated ultraviolet light absorber and the synergist.

TABLE III Evaluation 01' antioxidants in polypropylene (25 mil) rotary oven, 150 C Hours to fail 0.1% antloxidant plus 0.25% auti- 0.5% UV2 oxidant plus plus 0.3/ 0.5% UV-2 1 DSIDP 1 Product:

Results similar to those reported in Tables III and IV are obtained when the antioxidants of Table II are employed together with the indicated secondary antioxidants and ultraviolet absorbers.

Prod- Secondary uct antioxidant UV absorber G DSTDP 2-(3-t-butyl-2-hydroxy-5-methylphenyl)--chlorobenzotriazole.

H DL'IDP l 2-11ydroxyt-n-oetyloxybenzophenone.

I Tris-nonylphenyl- 4-dodecyloxy-Z-hydroxybenzophenone.

phosphite.

J 'Irllauryl trithio- 4-t-octylphenyl salicylate.

phosphite. DLTD Phcnylsalicylate.

M Tris-nonylphenyl- 2,4-dihydroxybenzophcnone.

phosphite.

N DS'IDP 2-hydroxyi-methoxybenzophenone.

O Trilauryl trlthio- 5-chloro-2-hydroxybenzophenone.

phosphite.

P DSTDP M-octylnhcnyl salicylate.

1 Dllaurylthiodipropionatm It should be noted that in all above examples of stabilizing compositions the use of a secondary antioxidant and an ultraviolet absorber is optional. However, for best results, said additives should be employed in conjunction with the antioxidants of this invention, especially the secondary antioxidant. These supplementary additives may be used in the amount of from about 0.05 to about 5% each, and preferably from about 0.1 to about 2% by weight of the substrate.

Besides activity in the oven ageing test, the novel antioxidants of the present invention are characterized by excellent color values (no discoloration during the oven ageing test) and good gas fading properties.

The present antioxidants are useful in protecting synthetic polymers such as polypropylene against oxidation in air, thermal degradation or deterioration by including in such substances, a stabilizing amount of the antioxidant which will vary between about 0.01 and 5% and preferably, from about 0.05 to about 1.0% by weight. The antioxidant can be incorporated into the synthetic polymers using conventional procedures. For example, the antioxidants of the present invention are incorporated into the material to be stabilized by any suitable means such as by milling the antioxidant on hot or cold mill rolls, by mixing it in by the use of a Banbury mixer or other wellknown devices of this nature or the antioxidant may be mixed with a polyolefin material in the form of molding powder and incorporated during extrusion or prior to extrusion or during injection molding. The antioxidant may even be incorporated into a solution of the polyolefin material and the solution may then be employed for the formation of films, for wet or dry spinning of fibers, monofilament and the like.

The examples set out above are to be considered as illustrative of the present invention and are not to be considered as restrictive. It is therefore to be understood that the invention is not limited to the specific embodiments set out above except as defined in the appended claims.

What is claimed is:

1. A compound of the formula:

(lower) alkyl where said (lower) alkyl has from 1 to 6 carbon atoms;

--R R R are each hydrogen, lower alkyl from 1 to 6 carbon atoms, phenyl, benzyl or -C H COOR, Where m is 0 to 6;

R is alkyl from 1 to 24 carbon atoms, cycloalkyl from 1 to 6 carbon atoms, phenyl and benzyl and when Q is OR the two R groups can be (CH Where n is 2 or 3, forming a cyclic 0,0- diester of phosphorothiolothionic acid.

2. A compound according to claim 1 wherein R is I(lower) alkyl (lower) alkyl 3. A compound according to claim 2 wherein Q is phenyl.

4. A compound according to claim 2 wherein Q is alkoxy.

5. A compound according to claim 1 wherein R R and R are hydrogen, R is 3,5-di-t-butyl-4-hydroxyphenyl and Q is phenyl.

6. A compound according to claim 1 wherein R and R are hydrogen, R is COOR, R is 3,5-di-t-butyl-4- hydroxyphenyl and Q is phenyl.

7. A compound according to claim 1 wherein R and R are hydrogen, R is CH COOR, R is 3,5-di-t-buty1-4- hydroxyphenyl and Q is phenyl.

8. A compound according to claim 1 wherein R and R are hydrogen, IR is methyl, R is 3,5-di-t-buty1-4-hydroxyphenyl and Q is ethoxy.

9. A compound according to claim 1 wherein R and 10 1 0 References Cited UNITED STATES PATENTS 2,876,156 3/1959 Bavley et a1. 260942 X 3,047,459 7/1962 Perini et al. 260941 X FOREIGN PATENTS 213,407 2/ 1961 Austria 260942 CHARLES B. PARKER, Primary Examiner R. L. RAYMOND, Assistant Examiner US. Cl. X.R.

GC 355 TJNTTTD STATES PATENT oTTTcT @ER'HFTQATE @F @ORREQ'HQN Patent No. 3 I 639 538 Dated February 1 I 1972 Eduard K. Kleiner Inventor(s) It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Page 1, Column 2, line 58, (R P(S)SH should read (R O) P(S)SH.

Page 2, Column 4, line 45 (d) structure portion CH COOR should read CH COOR Page 3, Table II, Part (0), structure CH =CHCOOR should read 2 6 CH2=CHCOORO Claim 9, R should be changed to "R and R should be changed to "R Signed and sealed this 28th day of November 19.72.

(SEAL) Attest:

EDWARD MJLETCHERJ'R ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents FORM PO-1050 (10-69) USCOMM-DC 6O376-P69 U 5. GOVERNMENT PRINTING OFFICE: 1969 ()36633 GC 355 UNITED STATES PATENT OFFICE fiERTIFICATE OF CGRREGTION Patent No. 3,639,538 Dated February 1, 1972 Eduard K. Kleiner Inventor(s) It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Page 1, Column 2, line 58, (R P (S) SH should read R 0 P .(S) SH Page 2, Column 4 line 45 (d) structure portion CH COOR should read CH COO 0 Page 3, Table II, Part (0) structure CH =CHCOOR should read CH =CHCOOR Claim 9, R should be changed to "R and R should be changed to "R Signed and sealed this. 28th day of November 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner' 'of Patents FORM PO-1050 (10-69) USCOMM-DC 60376-P69 U.S. GOVERNMENT PRINTING OFFICE H169 O366334 

